The novel use of a memory layer in a giant magnetoresistive position sensor design

A linear noncontact position sensor using Co/Cu giant magneto-resistance (GMR) multilayers as the sensing material and incorporating a magnetic memory layer has been designed and modeled. A magnetic head assembly acts as the position locator and the presence of a memory layer makes the throw length unlimited. A numerical model using charge sheets and finite elements has been used to optimize the physical dimensions of the magnetic layers for different magnetic materials and determine their spacing from the Co/Cu GMR sensing material. The output from the sensor has been simulated as the head moves back and forth along the track. These results show that hysteresis in the memory layer can be overcome by optimizing the head design. Using easily available materials, the modeling has shown that a device using second anti-ferromagnetic (AF) peak Co/Cu is realizable. The model has also be used to identify desirable material parameters for potential future engineered materials with the aim of utilizing high GMR first AF peak Co/Cu material in the sensor.